I haven't really come across such a remark in the suttas in Theravada. If the book doesn't refer to any sutta in the canon the monk is probably writing down his own opinion.
On the contrary, in the Mangala sutta Buddha praised learnedness when answering a question by one of the devas regarding what brings the highest blessing to a person,
[Deva:]
Many devas and human beings give thought to protection, desiring
well-being. Tell, then, the highest protection.
[The Buddha:]
[..]
Living in a civilized land,
having made merit in the past,
directing oneself rightly:
This is the highest protection.
Broad knowledge, skill,
well-mastered discipline,
well-spoken words:
This is the highest protection.
Support for one's parents,
assistance to one's wife and children,
consistency in one's work:
This is the highest protection
[..]
Mangala sutta [Thanissaro Bhikkhu Trans]